Apparatus and method for preventing lime scale buildup in water heaters

ABSTRACT

An apparatus for preventing lime scale buildup in a water heater tank includes a curve-biased tube, the tube including an opening disposed at an end, a length of at least seventy-five percent of the circumference of an interior bottom of the water heater tank, and a plurality of holes disposed along the length that face radially inward when the tube is arranged in a substantially annular configuration in accordance with its curve-biased position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 13/011,272, filed Jan. 21, 2011, which claims priority to U.S. Provisional Patent Application Ser. No. 61/418,497, filed Dec. 1, 2010, the entire disclosures of which are incorporated by reference herein.

BACKGROUND OF INVENTION

1. Field of the Invention

The presently claimed invention relates to water heaters. More specifically, the presently claimed invention relates to apparatus and methods for preventing lime scale buildup in water heaters.

2. The Prior Art

For over 50 years many attempts have been made in the plumbing industry to find ways to reduce lime scale formations on the bottoms of commercial water heater tanks. In addition to reducing the efficiency of a water heater, lime scale formations on the tank bottoms is one of two basic factors that cause commercial tanks to fail within the tank warranty periods or shortly after the warranties expire.

As lime scale forms on the inside of the tanks on the bottom surfaces it acts as an insulator causing the temperatures of the tank bottoms to rise even higher. As the temperatures of the tank bottoms increase more lime scale forms and the cycle continues. Eventually the tank bottoms or one of the welds that attaches flues to the tank bottoms fails. Per the manufacturers' warranties, this would only be a normal expectation as lime scale builds up and causes excessively high temperatures on the tank bottoms followed by intermittent cooling as new cold water enters the tank.

Lime scale forms on tank bottoms as water is heated due to calcium carbonate which is present in varying degrees in the solids and sediments in all water. Harder water with the higher grains contains the highest amounts of calcium carbonates. The amount of lime scale that forms is directly related to the amount of calcium carbonates present in the solids and sediments. Water heater manufacturers recognizing that lime scale formations are the basic reason for premature tank failures, all put hand hole clean out openings in their commercial tanks and require the end uses to clean out the lime scale and sediments on a regular basis in order to keep the tank warranties valid.

In attempts to reduce premature failures in commercial tanks, many companies have developed methods that will supposedly stop or control the formation of lime scale. Water softeners are perhaps one of the most successful methods. They can reduce or stop lime scale formations if they are adequate in size. In commercial water heater applications however, they are rarely used due to the fact that they would be too expensive if they were sized to handle the high volumes of water passing through most commercial water heaters. In addition, soft water causes anodes to spend themselves very rapidly and in most of the commercial water heater tanks it is very difficult to replace the tank anodes. Consequently even though lime scale is not formed in soft water, tanks using water softeners can easily develop leaks in other areas as the anodes are depleted.

In addition to water softeners, various chemical products have been developed that claim to stop lime scale. They have been unsuccessful however, in commercial water heaters, largely because the inconsistent and irregular volumes of water used in commercial water heater applications make it difficult to determine the proper amount of chemicals needed for various installations.

In the past 20 years several other things have been marketed that also claim to stop lime scale from forming on the tank bottoms. The use of magnets in water lines for instance, with the claim that the magnets will change the composition of the water deposits, has been tried by one water heater manufacturer as well as many on line retailers. It is now commonly recognized in the industry however that such devises will not work for the volumes of water being used in commercial water heaters.

Another product has been marketed in a commercial water heater that is similar to a spray nozzle. This device which is on the end of the cold water inlet is alleged to create a swirling action that will move solids in the water away from the tank bottoms so that they will not form lime scale. This device however is ineffective, since water can only be moved through this device when hot water is being drawn from the tank and cold water is coming into the tank. Since water comes into a tank only when water is moving out of the tank, the incoming water will take the path of least resistance and move upward toward the hot water outlet rather than downward toward the tank bottom.

In addition, the required location of the swirling device itself voids its effectiveness. In order for a water heater to pass ANSI on and off cycling requirements, the cold water inlet tubes must be terminated at a distance too far away from the water heater bottoms to enable the swirling water coming from the end of cold water tubes to reach the tank bottoms and be effective at reducing lime scale. In most cases the ends of such tubes are approximately 12″ away from the tank bottoms and an additional 14″ away from the center of the tank bottoms.

The inability of any of the devices presently being marketed to reduce the large number of premature failures due to lime scale formations in commercial water heaters can only lead one to the conclusion that as long as sediment and solids containing calcium carbonate are present in a tank, they will form lime scale on the tank bottoms when the water being heated remains motionless on the tank bottoms.

The apparatus and method of the presently claimed invention overcomes the past difficulties of moving solids away from the center of the tank bottoms by providing a means of constantly moving water to the center of the tank bottoms 24 hours a day. The constant flow of the water on to the center of the tank bottoms as provided by the invention consequently moves sediment and other solids both containing calcium carbonate away from the center of the tank bottoms so that they will be drawn out of the tank with the hot water before the calcium carbonate has a chance to form lime scale. The presently claimed invention, while not claiming to eliminate lime scale completely, significantly reduces lime scale formations and thereby extends the lives of commercial water heater tanks. In doing so, the presently claimed invention also significantly reduces energy costs by maintaining the water heaters' original efficiencies. Lime scale build up can cause commercial water heaters to lose as much as twenty percent of their efficiencies in as little as two years in areas with hard water. Furthermore, the invention provides a means of meeting water heater manufacturers' warranty requirements by providing a workable means for reducing the build up of lime scale in the tank.

BRIEF DESCRIPTION

According to one aspect of the presently claimed invention, a water heater assembly includes a water heater tank having a drain valve coupling opening for a drain valve, or larger coupling openings, disposed in a tank wall thereof. A re-circulating pump then has an output in fluid communication with the inside of the tank through either the drain valve coupling opening or through another tank coupling with a tube extending inside the tank from either one of these openings. When the drain valve opening coupling is used, the drain valve is usually repositioned to the center of a tee that is connected to the re-circulating pump. The tube then has a distal end positioned proximate to the center of the bottom of the tank in an orientation such that water flowing out of the distal end of the tube creates currents that move solids and sediment deposits away the center of the tank bottom in order to prevent lime scale from forming on the inside of the tank.

According to another aspect of the presently claimed invention, a water heater includes a tank that includes an interior bounded by a top and a bottom connected by a wall, and a drain valve coupling opening disposed in the wall. The water heater further includes a tube that is disposed in the interior of the tank. The tube is arranged circumferentially around the bottom of the tank and includes a plurality of holes that face radially inward towards the center of the bottom of the tank. The tube is in fluid communication with an external water supply line through the drain valve coupling opening in the tank. Moreover, the tube is arranged such that water flowing out of the holes creates turbulence that moves solids and sediments away from the center of the bottom of the tank.

According to yet another aspect of the presently claimed invention, an apparatus for preventing lime scale buildup in a water heater tank includes a curve-biased tube. The tube includes an opening disposed at an end, a length of at least seventy-five percent of the circumference of an interior bottom of the water heater tank, and a plurality of holes disposed along the length that face radially inward when the tube is arranged in a substantially annular configuration in accordance with its curve-biased position. When disposed circumferentially around the interior bottom of a water tank and placed in fluid communication with an external water supply line, water flowing out of the holes creates turbulence that moves solids and sediments away from the center of the bottom of the tank.

According to a further aspect of the presently claimed invention, a method for preventing lime scale buildup in a water heater tank includes providing a flow of water into the water heater tank and directing the flow of water to a position proximate to the bottom of the tank. The flow of water into the water heater tank can be supplied from a re-circulating pump. A hose or length of tubing may be installed inside the water heater tank and positioned such that an end thereof is located proximate to the bottom of the water heater tank. The flow of water is directed to create currents that move solids and sediment deposits in the tank in order to prevent lime scale from forming on the inside of the tank. This may be accomplished by directing the flow of water towards a center region of a bottom of the water heater tank to create currents that move solids and sediment deposits away from the center of the tank bottom.

According to another aspect of the presently claimed invention, a method for preventing lime scale buildup in a water heater tank includes providing a flow of water into the water heater tank, splitting the flow into a plurality of sub-flows arranged circumferentially around the bottom of the tank, and directing the sub-flows radially inward towards the center of the bottom of the tank. The sub-flows create currents that move solids and sediment deposits away from the bottom of the tank. Because the solids and sediments are constantly moving away from the bottom of the tank, they have little time to settle and form lime scale.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a perspective view of an exemplary embodiment of a water heater assembly in accordance with the presently claimed invention.

FIGS. 2A and 2B are diagrams of two additional exemplary embodiments of a water heater assembly in accordance with the presently claimed invention.

FIG. 3 is a diagram of an exemplary method of providing a flow of water into a water heater tank in accordance with the presently claimed invention.

FIG. 4A and 4B are diagrams of exemplary embodiments of a water heater assembly that show various hose positions in accordance with the presently claimed invention.

FIG. 5 is a diagram of another exemplary method of providing a flow of water into a water heater tank in accordance with the presently claimed invention.

FIG. 6 is a perspective view of another exemplary embodiment of a water heater in accordance with the presently claimed invention.

FIG. 7 is a perspective view of an exemplary embodiment of an apparatus for preventing lime scale buildup in a water heater tank in accordance with the presently claimed invention.

FIG. 8 is a flow diagram of an exemplary method for preventing lime scale buildup in a water heater tank in accordance with the presently claimed invention.

FIG. 9 is a flow diagram of another exemplary method for preventing lime scale buildup in a water heater tank in accordance with the presently claimed invention.

DETAILED DESCRIPTION

Persons of ordinary skill in the art will realize that the following description of the presently claimed invention is illustrative only and not in any way limiting. Other embodiments of the invention will readily suggest themselves to such skilled persons.

The presently claimed invention directs a continuous flow of water to the center of the bottom of a water heater tank. This continuous flow of water, as provided in the invention, moves solids and sediments away from center of the bottom heating area so that they can exit the tank as hot water is drawn. In some embodiments, a re-circulating pump, a feature common on nearly all commercial water heaters, may be used. Other embodiments, as discussed further below, may be used without a re-circulating pump.

The presently claimed invention employs a tubular assembly. All materials used in the invention are capable of withstanding the high temperatures generated in the water heating tank while they at the same time, comply with FDA and ANSI requirements for use in systems using potable water. As discussed further below, some exemplary embodiments may be installed through the hand hole clean out opening in a water heater tank by placing it into position on a tube extending from a nipple that is installed in the drain valve coupling opening or a water inlet coupling opening. Such openings are common among commercial water heater tanks. The opposite end of the nipple (outside the tank) utilizes a tee that connects to the drain valve coupling (through a re-circulating pump, in some exemplary embodiments). The drain valve is then connected to the center of the tee and the tank can still be drained in a normal manner through the drain valve.

Referring first to FIG. 1, a diagram shows a typical commercial tank 10 having a hand hole cleanout opening 12 bordered by flange 14. Cover 16 is bolted over the hand hole cleanout. Tank 10 also includes a location 18 near the bottom for the drain valve coupling. A tee fitting 20 is provided, one end 22 of the tee 20 coupling to the drain valve and the other end 24 where the re-circulating pump 26 is attached. A flexible tube 28 is attached to the drain valve coupling opening on the inside of the tank. Water flows through this flexible tube 28 directly to the center of the tank bottom where it then moves solids and sediment deposits away the center of the tank bottom as indicated by arrows 30, before lime scale can be formed.

FIGS. 2A and 2B show two different positions of the lime scale reducer in the tank according to illustrative embodiments of the presently claimed invention. For commercial water heater installations the drain valve 22 is normally removed and a nipple is installed. The re-circulating pump 26 is then installed at the end of the tee fitting 20 and the drain valve 22 is installed in the middle of the tee 20. According to the presently claimed invention, a special nipple containing a short tube 28 is placed so that it extends into the tank through tank wall 18. By reaching through the hand hole clean out opening, a first end of the assembly according to the invention is then connected to the tube portion of the special nipple by inserting a fitting over the tube extending from the special nipple. This can be done with or without a bonding agent since the re-circulating pump operates at a very low pressure.

In another exemplary embodiment shown in FIG. 2B, two elbows 32 and 34 and a close nipple 36 are used to provide a method of raising the assembly slightly higher than the drain valve opening to provide clearance for radius type bottoms that are used in some commercial water heater tanks. In another embodiment, a flare type fitting is bonded directly into the tube extending out of this nipple. The assembly is constructed of appropriate fittings from front to back, including an appropriate opening close to the end of the assembly for the water outlet. Water flows through this outlet directly to the center of the tank bottom where it then moves solids and sediment deposits away the center of the tank bottom, before lime scale can be formed.

Referring now to FIG. 3, a diagram shows an illustrative way of coupling through the tank wall to provide flow from the recirculation pump or directly from the external water supply line into the tank according to the presently claimed invention. Tank wall 40 has a flange 42 attached to it by a means such as welding as shown by weld beads 44. A plug (not shown) may be threaded into the flange 42 if the invention is not used. If the invention is used, the plug is removed and a nipple 44 is threaded into flange 42.

Nipple liner 46 is disposed within nipple 44. In some exemplary embodiments, a fitting 48 is friction-fitted or bonded inside a barbed end 50 of fitting 48 (or optionally outside of nipple liner 46, depending on whether the tank has a convex or planar bottom) that extends at an angle of 0° or, for example, upwards or downwards at 90° from the body of fitting 48 as shown in dashed lines 50. An appropriate length of tubing or hose may be mounted on barbed end 48. In other exemplary embodiments, the tubing or hose may slip directly over the nipple liner inside the tank. Persons of ordinary skill in the art will readily recognize that there are other possible ways in which the tubing or hose may be coupled through the tank wall to the recirculation pump or directly to the external water supply line.

Fittings and flexible tubes are referred to in several places in the present disclosure. At the present time nylon, polypropylene, Teflon, CPVC, and one specific hose would all comply with ANSI requirements for this application. There are however, additional rubber hoses that would also meet ANSI requirements if they were tested for compliance. The definition of flexible tubes therefore, also includes rubber hoses.

Tubing and hoses suitable for use in the presently claimed invention should be flexible enough to be placed between the water heater tank flue tubes and still meet the ANSI temperature requirements for use inside a water heater tank. Material inside the tanks must not melt or distort if temperatures go a high as 230 degrees Fahrenheit. This is to insure that in the event of a malfunction of the controls on the water heater, the high limit safety device would shut the burner off before serious damage could occur from objects inside the tank melting and clogging pipes or damaging the tank. In addition to this, nothing inside the tank is permitted to emit a foul taste or odor to the water. Consequently tubes or fittings must meet FDA requirements for use with food or potable water. Further, all materials in the tanks must be capable of withstanding tank working pressures of 150 PSI and they all must be compatible with glass lined tanks incorporating anodes.

One example of a hose that meets all of these requirements is marketed by the NovaFlex Group of Richmond Hill, Ontario, Canada as Number 6506. This particular hose is usually employed in the food processing business and requires very few fittings. It can be attached to the nipple liner discussed previously or it can be attached to a 90 degree elbow pointing downward. The hose can then be placed in position in the center of the tank bottom where a second fitting will direct water away from the center of the tank bottom and move away the solids. This hose is also heavier than water and it will stay in position and not float upward.

Referring now to FIGS. 4A and 4B, two diagrams illustrate exemplary connections of hoses to fittings (such as the one depicted in FIG. 3) to provide a flow of water into a water heater tank according to the presently claimed invention. In both FIGS. 4A and 4B a water heater tank includes tank wall 60. A combustion chamber 62 includes a burner 64. Multiple flues 68 extend through tank bottom 68, which in FIG. 4A is flat and in FIG. 4B is convex.

In FIG. 4A, angled nipple fitting 70 extends through tank wall 60 and a length of tubing or hose 72 inside of the tank is coupled to a nipple liner as shown in FIG. 3. Tubing or hose 72 extends downward where it will bend between the flues and be positioned such that its end is located near the center of the bottom 68 of the tank. The flow of water driven by the re-circulating pump (not shown) is indicated at dashed line 74.

In FIG. 4B, the tank bottom 68 is convex. Straight nipple fitting 76 extends through tank wall 60 and a length of tubing or hose 72 inside of the tank is coupled to a nipple liner as shown in FIG. 3. Tubing or hose 72 can be bent upward to match the radius of the tank bottom simplifying the positioning. The hose 72 is flexed and positioned such that its end is located near the center of the convex bottom 68 of the tank. The flow of water driven by the re-circulating pump (not shown) is indicated at dashed line 78.

Referring now to FIG. 5, an embodiment of the invention is shown that can be implemented in tanks that do not have hand-hole cleanouts. Tank 80 is equipped with flange 82. A length of tubing or hose 84 is fed through the hole in flange 82 and positioned in tank 80. Tubing or hose 84 is fed through gasket 86 to provide a water-tight seal and is held in place using fitting 88 that may be bolted onto flange 82.

The assembly is composed of tubes and fittings, either threaded, bonded or clamped, that will extend to the center of all commercial water heaters. The assembly may be placed into position so that the open outlet area is positioned in an area close to the middle of the tank bottom. To accomplish this the tubes used in the invention are flexible, thereby providing a means for the assembly to make turns around the outer water heater flue tubes so that the water flow exit on the assembly can be located close to the center of the tank bottom facing downward. In other embodiments, the openings can be on the sides of the assembly or above the main tube assembly.

The presently claimed invention can utilize a heavy hose or tube that will not float upward as well as a lighter tube that employs a weight to hold it in position. The exemplary embodiments shown in FIGS. 1-5 can also utilize a metal type tube that will not bend. In such an embodiment a tube would be pre-bent for a specific heater with specific flue tube locations and the metal flow tube would be coated inside and out with water heater porcelain to prevent rust. All embodiments in accordance with the presently claimed invention include outlets that will move solids and sediment away from the center of the tank bottom on a continuous basis.

Referring now to FIG. 6, in another exemplary embodiment of the presently claimed invention, a water heater 90 includes a tank 92. Tank 92 includes an interior bounded by a top 94 and a bottom 96 connected by a wall 98, and a drain valve coupling opening 100 disposed in the wall 98. Tank 92 further includes a tube 102 disposed in the interior of the tank 92. The tube 102 is arranged circumferentially around the bottom 96 of the tank 92 and includes a plurality of holes 104 that face radially inward towards the center of the bottom 96 of the tank 92. By encircling the center of the bottom 96 and directing water radially inward, this exemplary embodiment minimizes lime scale formation over the entire surface of the bottom 96. In doing so, it increases the efficiency of a water heater between 1 and 1.5 percent. In today's energy conscious world, such efficiency increases are important and extremely desirable. In some embodiments, the tube 102 may comprise a plurality of individual tube segments 103 that are in fluid communication with one another through a plurality of union fittings 105. In such embodiments, the holes 104 may be disposed in the union fittings 105 rather than the individual tube segments 103. In other embodiments, the tube 102 may comprise a single length of tube (not shown) and the holes 104 may be disposed directly in the tube 102.

The tube 102 is in fluid communication with an external water supply line (not shown) through the drain valve coupling opening 100 and is arranged such that water flowing out of the holes 104 creates turbulence that moves solids and sediments away from the center of the bottom 96 of the tank 92. In one exemplary embodiment, the tube 102 may coupled to the external water supply line through a re-circulating pump (not shown). In another exemplary embodiment, water heater 90 may be utilized without a re-circulating pump. In such cases, a separate line that is smaller in diameter than the external water supply line may deliver a portion of the flow from the external water supply line into tube 102 through a nipple (as described above with regard to other exemplary embodiments) in the drain valve coupling opening 100. As persons of ordinary skill in the art will readily recognize, this can be accomplish by placing a tee and a reducer in the external water supply line. These embodiments may be coupled through the drain valve coupling opening 100 disposed in the wall 98 in the same manner as discussed above with respect to other exemplary embodiments and shown, for example, in FIG. 3.

In some exemplary embodiments, water heater 90 may include a hand hole clean out opening 104 the wall 98 of the tank 92. In such embodiments, the physical dimensions of the tube 102 may dictate that the tube 201 can only be installed in the interior of the tank 92 through the hand hole clean out opening 104. In other exemplary embodiments, water heater 90 may not include a hand hole clean out opening 104. In such embodiments, the tube 102 may be pre-installed in the interior of the tank 92 before the bottom 96 of the tank is attached to the wall 98 during assembly. Persons of ordinary skill in the art will readily recognize that, in embodiments in which tube 102 is pre-installed before assembly of tank 92, tube 102 must be formed of materials that can withstand the heat generated during the assembly process.

In yet another exemplary embodiment of the presently claimed invention, an apparatus for preventing lime scale buildup in a water heater tank may include a curve-biased tube 106. The tube 106 includes an opening 108 disposed at an end, a length of at least seventy-five percent of the circumference of an interior bottom of a water heater tank (not shown), and a plurality of holes 110 disposed along the length that face radially inward when the tube 106 is arranged in a substantially annular configuration in accordance with its curve-biased position. The opening 108 is capable of coupling to, and fluidly communicating with, a nipple 112 in the valve coupling opening of a water tank (not shown). An external water supply line may then be coupled in fluid communication with the tube 106 through the nipple 112. The length of tube 106 must allow for the tube 106 to be substantially encircle the center of the interior bottom of the water heater tank. By encircling the center of the bottom and directing water radially inward, this exemplary embodiment minimizes lime scale formation over the entire surface of the bottom. In some embodiments, the tube 106 may comprise a plurality of individual tube segments 114 that are in fluid communication with one another through a plurality of union fittings 116. In such embodiments, the holes 110 may be disposed in the union fittings 116 rather than the individual tube segments 114. In other embodiments, the tube 106 may comprise a single length of tube and the holes 110 may be disposed directly in the tube 106.

Additionally, FIG. 8 shows a further an exemplary method for preventing lime scale buildup in a water heater tank. At step 118, a flow of water is provided into the water heater tank using an external water supply line. Next, at step 120, the flow of water is split into a plurality of sub-flows that are then arranged circumferentially around the bottom of the tank. Finally, at step 122, the sub-flows are directed radially inward towards the center of the bottom of the tank. The sub-flows create currents that move solids and sediment deposits away from the bottom of the tank. Because the solids and sediments are constantly moving away from the bottom of the tank, they have little time to settle and form lime scale. In some exemplary methods, step 118 may include providing a flow of water into the water heater tank through a re-circulating pump. In other exemplary methods, step 118 may not include providing a flow of water into the tank through a re-circulating pump.

As shown in FIG. 9, in yet another exemplary method, the steps of splitting the flow into a plurality of sub-flows arranged circumferentially around the bottom of the tank and directing the sub-flows radially inward towards the center of the bottom of the tank may include further substeps. After a flow of water is provided into the water heater tank at substep 124, a tube having a plurality of holes is provided at substep 126. In some embodiments, substep 126 may include providing a tube that includes a plurality of individual tube segments coupled together through a plurality of union fittings, each union fitting having at least one hole. In other embodiments, step 126 may include providing a single length of tube having a plurality of holes disposed directly therein.

Next, at substep 128, the tube is placed in the interior of the water heater tank through a hand hole clean out opening in a wall of the tank. In other exemplary embodiments, the tube may be placed in the interior of the water heater tank through an alternate opening in the wall. At substep 130, the tube is arranged circumferentially around the bottom of the tank such that the holes face radially inward towards the center of the bottom of the tank. Step 130 may be accomplished using a number of tools that will be readily appreciated by persons of ordinary skill in the art. For example, one such tool may include a plumbing snake. Finally, at substep 132, the tube is placed in fluid communication with the external water supply line. In some exemplary embodiments, the tube may be coupled to the external water supply line through a re-circulating pump. Notably, in another exemplary method that is particularly useful for water heater tanks without a hand hole opening, the tube may also be placed in the interior of the water heater tank prior to assembling the tank.

The assemblies used in the presently claimed invention can employ barb fittings, thread-to-barb fittings, threaded fittings, and bonding type fittings commonly referred to as weld fittings along with appropriate tubing. The fittings may be formed from various grades of materials complying with ANSI heat and food grade standards covering materials for this type of use. All fittings and tubes according to the presently claimed invention will be capable of meeting or exceeding the heat and pressures requirements for these installations.

While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications than mentioned above are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the appended claims. 

What is claimed is:
 1. A water heater, comprising: a tank, the tank including an interior bounded by a top and a bottom connected by a wall, and a drain valve coupling opening disposed in the wall; and a tube disposed in the interior of the tank, the tube arranged circumferentially around the bottom of the tank and including a plurality of holes facing radially inward towards the center of the bottom of the tank, the tube in fluid communication with an external water supply line through the drain valve coupling opening and arranged such that water flowing out of the holes creates turbulence that moves solids and sediments away from the center of the bottom of the tank.
 2. The water heater of claim 1, wherein the tube is coupled to the external water supply line through a re-circulating pump.
 3. The water heater of claim 1, wherein the water heater tube is pre-installed in the interior of the tank before the bottom is attached to the wall.
 4. The water heater of claim 1, wherein the tube comprises a plurality of individual tube segments in fluid communication with one another through a plurality of union fittings.
 5. The water heater of claim 4, wherein the holes are disposed in the union fittings.
 6. The water heater of claim 1, wherein the tube comprises a single length of tube.
 7. An apparatus for preventing lime scale buildup in a water heater tank, comprising: a curve-biased tube, the tube including an opening disposed at an end, a length of at least seventy-five percent of the circumference of an interior bottom of the water heater tank, and a plurality of holes disposed along the length that face radially inward when the tube is arranged in a substantially annular configuration in accordance with its curve-biased position.
 8. The apparatus of claim 7, wherein the tube comprises a plurality of individual tube segments in fluid communication with one another through a plurality of union fittings.
 9. The apparatus of claim 8, wherein the holes are disposed in the union fittings.
 10. The apparatus of claim 7, wherein the tube comprises a single length of tube.
 11. A method for preventing lime scale buildup in a water heater tank, comprising: providing a flow of water into the water heater tank using an external water supply line; splitting the flow into a plurality of sub-flows arranged circumferentially around the bottom of the tank; and directing the sub-flows radially inward towards the center of the bottom of the tank.
 12. The method of claim 11, wherein providing a flow of water into the water heater tank comprises providing a flow of water into the water heater tank from a re-circulating pump.
 13. The method of claim 11, wherein splitting the flow into a plurality of sub-flows arranged circumferentially around the bottom of the tank, and directing the sub-flows radially inward towards the center of the bottom of the tank comprises: providing a tube having a plurality of holes; placing the tube in the interior of the water heater tank through an opening in a wall of the tank; arranging the tube circumferentially around the bottom of the tank such that the holes face radially inward towards the center of the bottom of the tank; and placing the tube in fluid communication with the external water supply line.
 14. The method of claim 13, wherein the opening is a hand hole clean out opening.
 15. The method of claim 11, wherein arranging the tube circumferentially around the bottom of the tank such that the holes face radially inward towards the center of the bottom of the tank comprises directing the position of the tube using a plumbing snake.
 16. The method of claim 11, wherein splitting the flow into a plurality of sub-flows arranged circumferentially around the bottom of the tank, and directing the sub-flows radially inward towards the center of the bottom of the tank comprises: providing a tube having a plurality of holes; placing the tube in the interior of the water heater tank prior to assembling the tank; arranging the tube circumferentially around the bottom of the tank such that the holes face radially inward towards the center of the bottom of the tank; assembling the tank; placing the tube in fluid communication with an exterior water supply line; and using the exterior water supply line to provide a flow of water through the tube.
 17. The method of claim 11, wherein providing a tube having a plurality of holes comprises providing a plurality of individual tube segments coupled together through a plurality of union fittings having a plurality of holes.
 18. The method of claim 11, wherein providing a tube having a plurality of holes comprises providing a single length of tube having a plurality of holes. 